Options for breaking the lifecycle of Macrophomina phaseolina

Authors: Henry, Peter

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/16/2022
Publication Date: 3/16/2022
Citation: Henry, P.M. 2022. Options for breaking the lifecycle of Macrophomina phaseolina. Driscoll's Global Plant Health Meeting: Disease and Pest Management in Berry Fruit Production, March 16, 2022 (virtual).

Interpretive Summary:

Technical Abstract: Disease caused by Macrophomina phaseolina is an important constraint on strawberry production worldwide. Traditionally, this pathogen was managed by pre-plant soil fumigation, but risks to the environment and human health have motivated a search for alternatives to this practice. An improved understanding of the ecology of this pathogen could help to devise fumigant-free management strategies. For example, it is assumed that M. phaseolina grows to high abundance on diseased tissues and the incorporation of these tissues into soil by tillage will lead to higher soil abundance of this pathogen. If true, then removing diseased or symptomatic plants from the field could reduce the amount of M. phaseolina in the soil and disease severity in subsequent seasons. The objective of this study was to improve our understanding of the lifecycle of M. phaseolina by: 1) quantifying the abundance of M. phaseolina on strawberry tissues, and 2) testing if the removal of infested crop debris could affect soil abundance, yield, or disease outcomes. We observed that the abundance of microsclerotia produced by M. phaseolina on host tissues was positively correlated with symptom severity. Symptomatic plants of three different susceptible cultivars contained similar concentrations of microsclerotia, suggesting that cultivar-specific differences are minimal when plants have the same symptom severity. Removing crowns did not have a significant effect on disease severity or yield in multiple trials, despite a major reduction in the inoculum returned to soil. The observed lack of efficacy could be a result of inoculum heterogeneity in the field, or because the amount of inoculum on the plants represented a relatively small proportion of the inoculum already in the soil.